Motor vehicle differential assemblies have been in common use for many years to allow one motor vehicle wheel on an axle to rotate at a different rate than the other motor vehicle wheel, such as would occur when a motor vehicle is turning, or two tires having different diameters are being used on the same axle.
A typical motor vehicle differential assembly includes a pair of meshing spider and side gears enclosed in a differential case. The case is usually a one-piece unit, having a ring gear bolted to the case. The case is usually made of cast iron. The spider gears, typically made of hardened steel, are held in place by a steel shaft, known as a pinion shaft, which passes through the differential case and the center of the spider gears. The spider gears, also commonly made of hardened steel, mesh with the side gears. When the ring gear and the differential case turn, the spider and side gears also turn. Power flow is through the case, into the spider gears, and on into the side gears. The side gears are splined to a pair of drive axles and transfer power to the drive axles which in turn transfer power to wheels which drive the vehicle.
Known prior art means for keeping the drive axles firmly engaged within the side gears include C-locks which are received by a circumferential groove provided in the end of the drive axle and which project radially beyond the periphery of the drive axle to contact a nearby face of the side gear. The C-lock has been known to work satisfactorily as long as the arrangement of the spider gears and the side gears provides a wide enough space between the side gear face and the pinion shaft to achieve adequate button thickness on the end of the drive axle where the groove for the C-lock is provided. Where the spider gear and side gear arrangement does not yield enough space to realize appropriate button thickness, alternate means of retaining the drive axles are required.
Another known retention means makes use of a cam plug and a set of balls mounted within an axially disposed recess at the end of the drive axle. Rotation of the pinion gear shaft moves the cam plugs further into the recess and the balls outwardly into locking engagement with an annular recess within the side gears. The pinion shaft is then secured against rotation by a pin or screw which extends therethrough.
The present invention achieves the same results as the above described known retention means using the cam plug and balls; but, with a greatly simplified design that is envisioned to provide a stronger link between the side gears and the drive shafts.